Contrasting styles of Laramide folding across the west-central margin of the Cretaceous Valles-San Luis Potosí carbonate platform, Mexico
Along the west-central limit between the Central Mexico Mesozoic Basin and the Valles-San LuisPotosí carbonate platform exist marked variations in style and intensity of Laramide folding (LateCretaceous-Early Tertiary). These variations are attributed to: 1) prominent inter- and intra-formationalcha...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2000 |
| País: | México |
| Institución: | Universidad Nacional Autónoma de México |
| Repositorio: | Redalyc-UNAM |
| OAI Identifier: | oai:redalyc.org:57217202 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=57217202 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias de la Tierra Valles Mexico Cretaceous San Luis Potosí Laramide folding |
| Sumario: | Along the west-central limit between the Central Mexico Mesozoic Basin and the Valles-San LuisPotosí carbonate platform exist marked variations in style and intensity of Laramide folding (LateCretaceous-Early Tertiary). These variations are attributed to: 1) prominent inter- and intra-formationalchanges in lithology and bedding thickness, and 2) overall thickness contrast between the Cretaceoussedimentary sequences accumulated in the basin and the carbonate platform. Tight, NE-verging folds withfold widths in the order of meters to tens of meters formed in those sites where only thinly bedded, slightlyargillaceous, basin calcareous turbidites were deposited. Folding is disharmonic in other localities wherethicker beds of slide breccias, made of clasts derived from the nearby carbonate platform, are interlayeredwith the basin turbidites. Breccia sheets controlled the formation of mesostructures, with fold widths in theorder of hundreds of meters, while second order folds, with fold widths in the order of meters, were formed inthe thinner bedded argillaceous limestones.Thick strata of shallow water carbonates, deposited in and around isolated patch reefs in the platforminterior, formed open (fold widths in the order of several kilometers), almost symmetrical folds with nearvertical axial planes. Despite significant facies changes in the limestone, associated with the presence ofpatch reefs, no variations in the folding style are related with them.The occurrence of anhydrite strata (Guaxcamá Formation) under isolated portions of the carbonateplatform interior also played an important role in the folding style, causing the tectonically inducedaccumulation of evaporite near the cores of some folds and/or formation of diapirs. This phenomenonmodified the structures and caused intense fracturing in the central portion of the Sierra de Guadalcázar. Infew places, anhydrite was injected along fractures in the limestone. Meteoric water infiltration anddissolution of the anhydrite developed intense karsticity and caused the formation of an extensive collapsebreccia. Division of the Sierra de Guadalcázar into several domains suggests that the structural anomalies inrespect to its immediate surroundings are concentrated in an area where anhydrites are exposed. Furthermore,the emplacement of the mid-Tertiary Cerro de San Cristóbal intrusive, a tin-bearing subvolcanic granite, didnot caused doming by forceful injection at the core of the Sierra de Guadalcázar. |
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